FYI - There's some new addition to Tomato's "qos-details" page and a new "qos-view transfers" page from Wes Gascoigne, which show the transmitted/received data per connection and the tx/rx rate per connection - in realtime. Inactive connections can be hidden. I think he may also be adding a checkbox soon to show the results only for a selected MAC or IP instead of the full list. You can check it out on my latest compile from the sites below (I compiled it only for the MIPSr2 routers though). This might be close to what you want? It ought to be possible to do all sorts of extra analysis later, too, adding up the connections would give total for a user, etc. Lots of possibilities!